MONOSTATIC SCANNING LIDAR USING A MULTI-FACETED POLYGON MIRROR AS ONE OF DUAL REDIRECTING ELEMENTS

LIDAR A BALAYAGE MONOSTATIQUE UTILISANT UN MIROIR POLYGONAL A FACETTES MULTIPLES EN TANT QUE DOUBLE REDIRECTION

English Abstract

A sensor comprises two independently rotatable elements. The first element comprises facets in a polygonal configuration fully rotatable about a first axis at a first angle relative to a source's beam axis and redirects energy incident on a facet at a second angle to a facet plane at a reflected angle equal in magnitude to the second angle as the first element is rotated. The second element may be a wedge mirror fully and independently rotatable about a second axis at a third angle to the beam axis that redirects energy at a fourth angle to the second axis, in a direction within the FOV, receives reflected energy to the first element for redirection toward an element interposed between it and the source that allows the source energy to pass unimpeded, and on to a detector. Correlating data from the detector and the source determines the target range.

French Abstract

Un capteur comprend deux éléments pouvant tourner indépendamment l'un de l'autre. Le premier élément comprend des facettes dans une configuration polygonale pouvant tourner complètement autour d'un premier axe selon un premier angle par rapport à un axe de faisceau de source et redirige l'énergie incidente sur une facette à un deuxième angle par rapport à un plan de facette à un angle réfléchi égal en amplitude au deuxième angle lorsque le premier élément est tourné. Le second élément peut être un miroir cunéiforme entièrement et indépendamment rotatif autour d'un deuxième axe selon un troisième angle par rapport à l'axe du faisceau qui redirige l'énergie selon un quatrième angle par rapport au second axe, dans une direction à l'intérieur du FOV, reçoit de l'énergie réfléchie vers le premier élément pour une redirection vers un élément interposé entre celui-ci et la source qui permet à l'énergie source de passer sans entrave, et sur un détecteur. La corrélation de données du détecteur et de la source détermine la plage cible.

Claims

WHAT IS CLAIMED IS:
1. A head for directing energy radiated from a source along a beam axis to
a coordinate
in a field of view (FOV) defined by at least one of azimuthal and elevational
orientations,
comprising:
a first energy-redirecting element comprising a plurality of facets organized
in a
polygonal configuration, the facets being fully rotatable about a first axis
that is at a first
angle relative to the beam axis, for rotating the facets about the first axis,
receiving the
radiated energy incident along the beam axis on a facet facing the source at a
second
angle to a plane of the facet and redirecting it at a reflected angle having a
magnitude equal
to the second angle as the first energy-redirecting element is rotated; and
a second energy-redirecting element fully and independently rotatable, in at
least
one of direction and rate relative to the first energy-redirecting element,
about a second axis
at a third angle to the beam axis, for receiving the redirected energy
incident thereon and
further redirecting it at a fourth angle to the second axis as it is rotated,
in a direction within
the FOV;
wherein the second axis is at a non-zero angle other than substantially 90
with each
of the beam axis and the first axis.
2. A head according to claim 1, wherein the FOV has a substantially
rectangular shape
oriented along its azimuthal and elevational orientations thereof.
3. A head according to claim 1 or claim 2, wherein the first energy-
redirecting element
is associated with a controlled orientation of the FOV and the second energy-
redirecting
element is associated with an uncontrolled orientation of the FOV.
4. A head according to claim 3, wherein the FOV extends substantially 85
along the
controlled orientation thereof.
5. A head according to any one of claims 3 through 4, wherein the FOV
extends
.. substantially 21 along the uncontrolled orientation thereof.
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Date Recue/Date Received 2022-04-11

6. A head according to any one of claims 1 through 5, wherein the first
angle is
substantially 90 .
35 7. A head according to any one of claims 1 through 6, wherein the
facets define a
regular polygon about a plane substantially normal to the first axis.
8. A head according to any one of claims 1 through 7, wherein the facets
are each
mirror surfaces for reflecting the radiated energy incident thereon at the
reflected angle.
9. A head according to any one of claims 1 through 8, wherein a third axis,
the beam
axis and the first axis define a right-handed cartesian coordinate system.
10. A head according to claim 9, wherein each of the facets substantially
define a plane
having an associated normal vector.
11. A head according to claim 10, wherein the plane of each facet is
substantially
parallel to the first axis and the associated normal vectors all lie in a
common plane normal
to the first axis.
12. A head according to claim 11, wherein the common plane is defined by
the third axis
and the beam axis and the first energy-redirecting element is associated with
the azimuthal
orientation of the FOV.
13. A head according to claim 12, wherein the common plane is defined by
the beam
axis and the first axis and the second energy-redirecting element is
associated with the
elevational orientation of the FOV.
14. A head according to any one of claims 11 through 13, wherein at least
one facet is
offset by a facet offset angle relative to the first axis.
15. A head according to claim 14, wherein the facet offset angle is
substantially less than
10 .
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Date Recue/Date Received 2022-04-11

16. A head according to any one of claims 9 through 15, wherein a
projection of the
second axis onto a first plane defined by the third axis and the beam axis is
substantially
along the third axis and a projection of the second axis onto a second plane
defined by the
70 third axis and the first axis is substantially at 45 with the first
axis.
17. A head according to claim 16, wherein the second axis is subjected to
at least one
positioning adjustment relative to the projection thereof onto at least one of
the first and
75 second planes.
18. A head according to any one of claims 1 through 17, wherein the fourth
angle is
substantially between 0 and 15 .
19. A head according to any one of claims 1 through 18, wherein the second
energy-
redirecting element is a second mirror surface.
20. A head according to claim 19, wherein the second energy-redirecting
element is a
substantially circular wedge mirror angled at the fourth angle relative to a
base normal to
the second axis.
21. A method for directing energy radiated from a source along a beam axis
to a
coordinate in a field of view (FOV) defined by at least one of azimuthal and
elevational
orientations, comprising actions of:
rotating a first energy-redirecting element comprising a plurality of facets
organized
in a polygonal configuration completely about a first axis that is at a first
angle relative to the
beam axis;
directing the energy from the source onto the first energy-redirecting element
at a
second angle to a plane thereof;
Date Recue/Date Received 2022-04-11

100 redirecting the energy incident on the first energy-redirecting
element, at a reflected
angle having a magnitude equal to the second angle, toward a second energy-
redirecting
element;C:
independently rotating, in at least one of direction and rate relative to the
first energy-
redirecting element, the second energy-redirecting element completely about a
second axis
105 at a third angle relative to the beam axis, wherein the second axis is
at a non-zero angle
other than substantially 90 with each of the beam axis and the first axis;
and
further redirecting the energy incident on the second energy-redirecting
element,
from the first energy-redirecting element, at a fourth angle to the second
axis in a direction
within the FOV.
46
Date Recue/Date Received 2022-04-11

Description

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MONOSTATIC SCANNING LIDAR USING A MULTI-FACETED POLYGON MIRROR AS
ONE OF DUAL REDIRECTING ELEMENTS
RELATED APPLICATIONS
Not Applicable
TECHNICAL FIELD
The present disclosure relates to scanning LIDARs and in particular to a
monostatic
scanning LIDAR optical ranging sensor with dual redirecting elements.
BACKGROUND
Optical ranging sensors for determining the profile of the surface of an
object relative to a
reference plane are known. In some applications, such sensors are often used
to
determine the range from the sensor to the object. Typically, they involve the
transmission
of an optical launch beam for reflection by the object and measurement of a
scattered
return beam from which the range to the object may be calculated. One such
system is
Light Detection And Ranging (LIDAR). Some LIDAR ranging systems measure the
time of
flight (TOF) of a collimated optical launch beam (typically using laser
pulses) and its
scattered return beam.
Monostatic LIDAR sensors, in which the launch beam and return beam are co-
aligned, are
relatively simple in structure. A simple example non-scanning monostatic LIDAR
sensor is
schematically shown in FIG. 1, in which the sensor 1 includes a beam source 2,
typically a
pulsed laser, a first lens 3, a beam splitter 4, a second lens 6, a detector 7
and a receiver
unit 11. A launch beam 8, which may be a laser beam, emanating from the beam
source 2,
passes through the first lens 3 and beam splitter 4, projecting the launch
beam 8 onto a
target 10, whose range is to be measured. The series of reflecting and
refracting elements
through which the launch beam 8 is passed is known as the sensor head.
The beam splitter 4 receives laser light reflected back from the target 10 and
is arranged so
that the component of the returned light 9 between the target 10 and the beam
splitter 4 is
co-aligned with the launch beam 8. Thus, the returned light 9 impinges upon
the detector 7.
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The beam splitter 4 reflects the return beam 9 at some angle, which in some
non-limiting
examples may be 90 , onto the detector 7 via the second lens 6. The range is
measured
by a receiver unit 11 based on correlation of information between the launch
beam 8 and
the detected returned light 9. Where the launch beam 8 is pulsed, a TOF
technique may be
employed based on the time interval between the pulsed launch beam 8 and
detected
returned light 9 and knowledge of the speed of light. In some non-limiting
examples, where
the launch beam 8 is a continuous wave (CW) signal, a phase detection
technique may be
employed based on the heterodyne phase difference between the CW launch beam 8
and
detected returned light 9. In some non-limiting examples, where the launch
beam 8 is a
CW signal, a triangulation technique may also be employed.
In some examples, the beam splitter 4 could be replaced by a (parabolic)
mirror (not
shown) facing the target 10, with a central aperture to allow the launch beam
8 to pass
through it.
In some examples, three-dimensional sensing may be obtained, by mounting the
sensor on
a pan-tilt unit that is re-oriented from time to time so that the launch beam
8 is reflected off
different locations on the surface of the target 10, or by interposing an
optical scanner (not
shown) between the beam splitter 4 and the target 10 to control the beam
direction and
direct the launch beam 8 along a two-dimensional grid (usually designated as
comprising X-
(azimuthal) and Y-coordinate (elevational) values) substantially normal to the
axis (Z-
coordinate) of the launch beam 8 and defining a reference plane. In such
examples, the Z-
coordinate, lying on an axis of the launch beam 8 that is normal to the
reference plane,
measures the range for each (x,y) coordinate pair. In such an arrangement, the
optical
scanner also receives laser light reflected back from the target 10 and is
arranged to
maintain the co-aligned arrangement between the component of the returned
light 9 and the
launch beam 8 between the target 10 and the optical scanner, so as to ensure
that the
detector 7 images the returned light 9 regardless of scanning angle (a concept
known as
auto-synchronization).
The maximum angular direction, at which the launch beam 8 may be directed by
the optical
scanner while remaining auto-synchronized, defines the field of view (FOV) of
the sensor.
Generally, it is considered beneficial to have as large a FOV as possible. In
particular, the
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use of optical ranging LiDAR sensors on such moving platforms, including
without limitation,
driver-assisted vehicles, benefit from a large FOV at least in a horizontal
(azimuthal or X-)
direction or orientation in order to identify incoming obstacles and provide
an ability to avoid
them.
Monostatic optics are often used in scanning LIDARs because of their
relatively small mirror
size. In some examples, it is beneficial to have as small a sensor package as
possible.
Moreover, in many applications for optical ranging sensors, the sensor is
mounted on a
moving platform, which may be ground-, underwater-, air- or even space-based,
to detect
objects in the platform's path or more generally, within its FOV, so as to
allow the platform
to be maneuvered toward, away or through the obstacles as desired, or
alternatively to map
the environment in which the platform is operating.
However, because monostatic LIDAR sensors co-align the returned light 9 with
the launch
beam 8, there is a risk that blooming from imperfections in the path of the
launch beam 8
especially at extremely short range, may, if they lie in the path of the
receiving optics,
saturate the detector 7, leading to anomalous range calculations. For this
reason,
monostatic LIDAR sensors typically do not detect the returned light 9 from
targets 10 that
are within a few meters' range. Furthermore, because the power of the returned
light 9
attenuates significantly as range increases, unless the detector 7 has an
extremely high
dynamic range, it also may not detect the returned light 9 if the target 10 is
distant.
In computer vision applications, such as for navigation of a robot or of an
autonomous
vehicle, a scanning LIDAR is often employed to acquire 3D imagery. In some
example
applications, such as mobile sensor applications, the specifications of such
scanning
LIDARs are challenging.
In some examples, the scanning LIDAR sensor may be further constrained to
occupy a
small volume and have a small weight with low power consumption.
In US Patent Application Publication No. 2005/0246065 filed by Ricard on 3 May
2005 and
published 3 November 2005 and entitled "Volumetric Sensor for Mobile Robotics"
there is
disclosed a volumetric sensor for mobile robot navigation to avoid obstacles
in the robot's
path that includes a laser volumetric sensor on a platform with a laser and
detector directed
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to a tiltable mirror in a first transparent cylinder that is rotatable through
3600 by a motor, a
rotatable cam in the cylinder tilts the mirror to provide a laser scan and
distance
measurements of obstacles near the robot. A stereo camera is held by the
platform, that
camera being rotatable by a motor to provide distance measurements to more
remote
objects.
The Ricard sensor employs a short-range off-the-shelf laser ranging system
capable of
providing measurements of less than substantially 50m. The laser ranging
system scans
only 33 lines vertically in a 360 helical scan pattern in is. Additionally,
the scanning
mechanism, employing a tiltable mirror, a protective cover and a window that
is rotated with
the mirror, is complex and may not be amenable to an increased scan rate.
Another such system is provided by Velodyne Lidar Inc. of Morgan Hill,
California. The
Velodyne model HDL-64 High Definition LiDAR is commonly found in autonomous
vehicles.
In the Velodyne system, the entire head, consisting of both scanning optics
and electrical
system) is spun. The scanning optics employs 64 pairs of lasers and detectors.
Such a
design employs special designs to pass data (at a rate of 1.3 M points per
second) and
power to the spinning head, which rotates at substantially 15 revolutions per
second. The
large number of pairs of lasers and detectors significantly affects the cost
of the device.
Moreover, the Velodyne sensor spans only 64 lines in the vertical direction
and has a short
maximum range of substantially 120m.
United States Patent No. 4,871,904 issued 3 October, 1989 to Metlitsky et
a/and entitled
"Multidirectional Optical Scanner" discloses a multidirectional scan pattern
that is generated
by two mirrors, each inclined at a tilt angle and rotated about an axis at an
angular speed.
The size and shape of the pattern are controlled by adjusting the tilt angles
and the angular
speeds.
The Metlitsky scanner acts as a bar code scanner and uses a continuous beam of
energy
with a faceted or oscillating element. The scan pattern has a void in the
middle. Given the
purpose for which the Metlitsky scanner is employed, this is in fact
desirable, especially
given that the energy is emitted in a continuous beam, because the void
reduces the risk
that the scanner will radiate energy at a customer's eye.
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United States Patent No. 7,336,407 issued 26 February, 2008 to Adams etal. and
entitled
"Scanner/Pointer Apparatus having Super-Hemispherical Coverage" discloses a
scanner
apparatus which has super-hemispherical coverage and includes a receiver, a
pair of
counter-rotating prisms, and a rotating mirror aligned with the pair of
counter-rotating
prisms. The rotating mirror and the pair of counter-rotating prisms guide an
observed
optical signal in a field of regard greater than that achievable through the
use of only the
pair of counter-rotating prisms. The apparatus may also include a laser that
generates an
optical signal guided by the prisms and the mirror toward an object of
interest in the field of
regard.
The prisms in the Adams et a/apparatus are constrained in that they rotate in
opposite
directions and the rotational speed of one of the prisms is a function of the
rotational speed
of the other prism, that is, the prisms are not independently rotatable.
PCT International Patent Application Publication No. W02013/177650 filed by
Neptec
Design Group Ltd. ("NDG") on 26 April, 2012 and entitled "High Speed 360
Degree
Scanning LIDAR Head" discloses a head for directing radiated energy from a
source to a
target at a coordinate in a field of view defined by at least one of azimuth
and elevation, that
comprises an angled element and a planar reflecting element. The angled
element rotates
about a first axis and redirects the beam, the redirection of the angled
element differing in at
least one of direction and extent as it is rotated. The reflecting surface
rotates about a
second axis parallel to the first. An axis normal to the surface extends at an
angle to the
second axis. The reflecting surface receives the redirected beam at a point
thereon and
reflects it in a direction within the FOV. A rotator may be positioned between
the source
and the angled element to support and independently rotate the angled element
and the
reflecting surface about the first and second axis without impeding the
energy.
While the NDG LIDAR head has two rotating elements, an angled element and a
planar
reflecting element, that are independently rotatable, they are constrained in
that the
rotational axes of both elements are parallel and, in some examples, co-axial.
The NDG LIDAR head accomplishes this by a dual hollow shaft rotator to
independently
rotate the angled element and the reflecting surface and to allow the energy
to be radiated
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from the source through the hollow shaft of the rotator onto the angled
element. The
hollow shaft rotator imposes practical limits on the minimum and maximum size
of the NDG
LIDAR head. The minimum size of the head is constrained by the fact that the
energy
beam that is directed onto the target passes through the hollow shaft. Unduly
reducing the
size of the head, and concomitantly the diameter of the hollow shaft, reduces
the effective
intensity of the return pulse energy. Since the energy is scattered by the
target upon which
it impinges, and not all of it will be reflected back to the detector, the
reduction in the
effective return pulse energy may impair the ability of the detector to gather
sufficient
energy in order to estimate the range to the target. At the same time, the
maximum size of
the head is constrained by the fact that the angled element and the reflecting
surface are
mounted onto the rotator and rotated thereby. Unduly increasing the size of
the head, and
concomitantly the diameter of the hollow shaft, increases not only the size of
the angled
element and the reflecting surface, but also the size of the rotator, and the
load that will be
borne by the motors driving them.
PCT International Patent Application No. PCT/CA2018/050566 filed 14 May, 2018
by
Neptec Technologies Corp. (NTC) and entitled "Dual Mirror Monostatic Scanning
LIDAR
Ranging Scanner" discloses a scanning ranging sensor (the first NTC sensor)
that
comprises first and second independently rotatable mirrors about respective
axes. The first
axis and the second axis are respectively at a first angle and a third angle
relative to a
source's incident radiation beam axis. The first mirror redirects the energy
at a second
angle to the first axis as it is rotated. The second mirror further redirects
the redirected
energy at a fourth angle to the second axis as it is rotated, in a direction
within the FOV,
receives returned energy from a target and redirects it to the first mirror to
be further
redirected toward an energy-redirecting element interposed between the source
and the
first mirror that allow unimpeded passage of the energy from the source, and
redirects the
returned energy to a detector. Correlating data from the detector with
corresponding data
from the source may determine the target range.
The first NTC sensor employs wedge mirrors for both the first and second
mirrors. Various
examples of the first NTC sensor respectively disclose a 60 x 40 elliptical
FOV (azimuth x
elevation), a 64 x 65 elliptical FOV and a 75 conical FOV. In the first NTC
sensor, the
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azimuthal and elevational orientations of the FOV tend to be highly correlated
and/or
coupled and the intensity of energy directed within the FOV tends to be
concentrated in the
centroid thereof.
In some examples, LiDAR sensors have employed a multi-faceted reflecting
mirror, also
known as a polygon mirror, to produce a large horizontal FOV. One example of
such a
sensor is Metlitsky et a/discussed elsewhere.
United States Patent No. 5,006,721 issued 9 April, 1991 to Cameron et a/and
entitled
"LiDAR Scanning System" discloses a LIDAR scanning system having a rotating
multifaceted polygon mirror for transmitting modulated light from one of its
facets to a
surface. Diffuse light reflected off said surface is received by another facet
of the polygon
mirror and reflected to a photo detector. The phase difference between the
transmitted and
received light is then used to compute the range of the surface from the
scanning system.
The intensity of the returned light is used to create a gray scale image of
the surface. The
use of separate optical paths for the transmitted and returned light, and a
small scanned
field of view results in an improved signal-to-noise ratio.
Cameron et a/employ a rotating eight-facet polygon mirror in combination with
an
orthogonal tilting mirror under galvanometer motor control. The laser is
reflected by a
polygon mirror in the horizontal direction and is reflected again in the
vertical direction by
the mirror driven by the galvonometer motor. While both the polygon mirror and
the tilting
mirror are capable of being independently rotated, the tilting mirror responds
to voltages
presented to the galvanometer motor and is tilted at an angle corresponding to
the
presented voltage. The Cameron etal. apparatus thus limits the movement of the
tilting
mirror to a limited angular tilt range and the tilting mirror is not fully
rotatable through a
complete 360 revolution. The apparatus measures range through frequency
modulation of
the laser emission, also known as frequency modulation (FM) continuous wave
(OW)
(FMCW).
The use of oscillating or rotating multi-faceted mirrors has also been
extensively used to
operate laser printers. Another type of application is for high-resolution
displays.
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An example of such an application is found in United States Patent
No.6,351,324 issued 26
February, 2002 to Flint and entitled "Laser Imaging System with Progressive
Multi-Beam
Scan Architecture". Flint discloses a progressive scan architecture for
displaying a two-
dimensional image by alternately scanning two or more laser beams, one after
the other
with a time delay between adjacent beams. The beams are arranged to become
incident
upon a polygon scanner in a row with an approximately uniform spatial
separation and an
approximately equal angle between adjacent beams. The polygon scanner scans
horizontally and a galvanometer-driven mirror scans vertically. Adjacent lines
are
progressively scanned in sequence from top to bottom, which advantageously
reduces or
eliminates psycho-visual effects and is tolerant of non-linearities in the
vertical scanner,
allowing use of a low-cost galvo mirror. Typically, the beams in the row are
arranged in
pairs, and only one beam from each pair will be scanning at any one time.
Embodiments
are described in which the duty cycle is slightly less than 50% and the laser
illumination is
switched between two interleaved beam scans thereby allowing a single
modulator to be
used for both beams which provides significant cost advantages and improves
system
efficiency. For full-color images, each of the beams described can incorporate
separate
red, green and blue (ROB) components which are individually modulated by
separate red,
green, and blue modulators. The system can be scaled up with one or more
additional
pairs of beams to improve resolution and/or increase pixel count without
requiring a high-
speed polygon scanner or a highly-linear galvo scanner. Furthermore, the
height of each
facet in the polygon mirror need by only one beam diameter and its length need
only be two
beam diameters, which allows the system to approach the minimum pixel size
attainable,
which is useful to provide high efficiency and high brightness in the image.
A typical two-dimensional scanner uses a polygon scanner for horizontal
scanning and a
galvonometer-actuated mirror that oscillates but is not fully rotatable about
at least a full
revolution, for vertical scanning.
United States Patent No. 7,598,848 issued 6 October, 2009 to Takagi etal.
(Takagi No. 1)
and entitled "Apparatus and Method of Pedestrian Recognition" discloses an
apparatus
having a laser radar that is used to recognize a pedestrian by detecting a
position of
reflective objects, mapping the objects in a two-dimensional coordinate
system, determining
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whether the objects are moving, and grouping moving objects closely located
with each
other. Based on a size of an object group, the pedestrian associated with the
object group
is accurately recognized.
The Takagi No. 1 LiDAR system is equipped with a single element, namely a 6-
facet
rotating polygon for the purpose of detecting pedestrians and other obstacles
from a
moving vehicle. Each mirror of the polygon has a slight increasing angle of
1.6 resulting in
the six mirrors reflecting light in six lines of different heights after a
full rotation of the
polygon. The resulting FOV is 36 (H) x 8.6 (V). Distances to objects are
calculated with
Time-of-Flight (TOF) method.
United States Patent No. 8,694,236 B2 issued 8 April, 2014 to Takagi (Takagi
No. 2) and
entitled "Road Environment Recognition Device and Method of Recognizing Road
Environment" discloses a radar unit that emits beams, and receives a
reflection beam
reflected by an object. A position of the object relative to a vehicle and an
attribute of the
object are recognized based on the emitted beams and the reflection beam. A
coordinate
position of the vehicle in an absolute coordinate is calculated based on a
traveling amount
of the vehicle and a coordinate position of the object is calculated based on
the calculated
position of the vehicle and the position of the object relative to the
vehicle. A road
environment of the vehicle is recognized based on the coordinate positions and
the attribute
of the object.
Takagi No. 2 uses the apparatus of Takagi No. 1 to map, in 3D, the road
details in front of
the moving vehicle. This may include the delineation of the road lanes, the
traffic sign,
obstacles, incoming vehicles, etc.
This background information is provided to reveal information believed by the
applicant to
be of possible relevance to the present invention. No admission is necessarily
intended, nor
should be construed, that any of the preceding information constitutes prior
art against the
present invention.
SUMMARY
9

It is an object of the present disclosure to obviate or mitigate at least one
disadvantage of
the prior art.
According to a broad aspect of the present disclosure, there is disclosed a
head for
directing energy radiated from a source along a beam axis to a coordinate in a
FOV defined
by at least one of azimuthal and elevational orientations, comprising: a first
energy-
redirecting element comprising a plurality of facets organized in a polygonal
configuration,
the facets being fully rotatable about a first axis that is at a first angle
relative to the beam
axis, for rotating the facets about the first axis, receiving the radiated
energy incident along
the beam axis on a facet facing the source at a second angle to a plane of the
facet and
redirecting it at a reflected angle having a magnitude equal to the second
angle as the first
energy-redirecting element is rotated; and a second energy-redirecting element
fully and
independently rotatable, in at least one of direction and rate relative to the
first energy-
redirecting element, about a second axis at a third angle to the beam axis,
for rotating at
least one complete revolution and receiving the redirected energy incident
thereon and
further redirecting it at a fourth angle to the second axis as it is rotated
in a direction within
the FOV; wherein the second axis is at a non-zero angle other than
substantially 90 with
each of the beam axis and the first axis.
In an embodiment, the FOV can have a substantially regular shape oriented
along its
azimuthal and elevational orientations. In an embodiment, the first energy-
redirecting
element can be associated with a controlled orientation of the FOV and the
second energy-
redirecting element can be associated with an uncontrolled orientation of the
FOV. In an
embodiment, the FOV can extend substantially 85 along the controlled
orientation thereof.
In an embodiment, FOV can extend substantially 210 along the uncontrolled
orientation
thereof.
In an embodiment, the first angle can be substantially 90 . In an embodiment,
the facets
can define a regular polygon about a plane substantially normal to the first
axis. In an
embodiment, the facets can each be mirror surfaces for reflecting the radiated
energy
incident thereon at the reflected angle.
Date Recue/Date Received 2022-04-11

In an embodiment, a third axis, the beam axis and the first axis can define a
right-handed
30 cartesian coordinate system. In an embodiment, each of the facets can
substantially define
a plane having an associated normal vector. In an embodiment, the plane of
each facet
can be substantially parallel to the first axis and the associated normal
vectors can all lie in
a common plane normal to the first axis. In an embodiment, the common plane
can be
defined by the third axis and the beam axis and the first energy-redirecting
element can be
35 associated with the azimuthal orientation of the FOV. In an embodiment,
the common
plane can be defined by the beam axis and the first axis and the second energy-
redirecting
element can be associated with the elevational orientation of the FOV. In an
embodiment,
at least one facet can be offset by a facet offset angle relative to the first
axis. In an
embodiment, the facet offset angle can be substantially less than 100. In an
embodiment, a
40 projection of the second axis onto a first plane defined by the third
axis and the beam axis
can be substantially along the third axis and a projection of the second axis
onto a second
plane defined by the third axis and the first axis can be substantially at 45
with the first
axis. In an embodiment, the second axis can be subjected to at least one
positioning
adjustment relative to the projection thereof onto at least one of the first
and second planes.
45 In an embodiment, the fourth angle can be substantially between 00 and
15 . In an
embodiment, the second energy-redirecting element can be a second mirror
surface. In an
embodiment, the second energy-redirecting element can be a substantially
circular wedge
mirror angled at the fourth angle relative to a base normal to the second
axis.
According to a broad aspect of the present disclosure, there is disclosed a
method for
50 directing energy radiated from a source along a beam axis to a
coordinate in a FOV defined
by at least one of azimuthal and elevational orientations, comprising actions
of: rotating a
first energy-redirecting element comprising a plurality of facets organized in
a polygonal
configuration completely about a first axis that is at a first angle relative
to the beam axis;
directing the energy from the source onto the first energy-redirecting element
at a second
55 angle to a plane thereof; redirecting the energy incident on the first
energy-redirecting
element, at a reflected angle having a magnitude equal to the second angle,
toward a
second energy-redirecting element; independently rotating, in at least one of
direction and
11
Date Recue/Date Received 2022-04-11

rate relative to the first energy-redirecting element, the second energy-
redirecting element
completely about a second axis at a third angle to the beam axis, wherein the
second axis
60 is at a non-zero angle other than substantially 90 with each of the
beam axis and the first
axis; and further redirecting the energy incident on the second energy-
redirecting element,
from the first energy-redirecting element, at a fourth angle to the second
axis in a direction
within the FOV.
11A
Date Recue/Date Received 2022-08-12

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Embodiments have been described above in conjunction with aspects of the
present
disclosure upon which they can be implemented. Those skilled in the relevant
art will
appreciate that embodiments may be implemented in conjunction with the aspect
with
which they are described but may also be implemented with other embodiments of
that
aspect. When embodiments are mutually exclusive, or are otherwise incompatible
with
each other, it will be apparent to those skilled in the art. Some embodiments
may be
described in relation to one aspect, but may also be applicable to other
aspects, as will be
apparent to those of skill in the art.
Some aspects and embodiments of the present disclosure may provide a dual
redirecting
element monostatic scanning LIDAR using a multi-faceted polygon mirror as one
of the
elements and a head therefor.
BRIEF DESCRIPTION OF THE DRAWINGS
Example embodiments of the present disclosure will now be described by
reference to the
following figures, in which identical reference numerals in different figures
indicate identical
elements and in which:
FIG. 1 is a schematic diagram of a non-scanning monostatic LIDAR optical
ranging sensor;
FIG. 2 is a schematic view of an example head for a monostatic scanning LIDAR
using a
multi-faceted polygon mirror element as one of dual redirecting elements
according to an
example;
FIG. 2A is a side cross-sectional view of the second redirecting element of
Fig. 2 according
to an example;
FIG. 3 is an example perspective schematic view of the sensor of Fig. 2,
according to an
example;
FIG. 4 is an isometric view showing the sensor of Fig. 2 within an enclosure
with an
aperture cover;
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FIG. 5 is an example schematic diagram illustrating respective contributions
of the multi-
faceted polygon mirror element and the second redirecting element of Fig. 2 to
produce the
FOV of the head of Fig. 2 according to an example;
FIG. 6 is a print out of an example of traces of a simulated projection of the
second
redirected launch beam in the launch portion of the sensor of Fig. 2; and
FIG. 7 is a flow chart showing method actions according to an example.
In the present disclosure, for purposes of explanation and not limitation,
specific details are
set forth in order to provide a thorough understanding of the present
disclosure. In some
instances, detailed descriptions of well-known devices and methods are omitted
so as not
to obscure the description of the present disclosure with unnecessary detail.
Accordingly, the system and method components have been represented, where
appropriate, by conventional symbols in the drawings, showing only those
specific details
that are pertinent to understanding the embodiments of the present disclosure,
so as not to
obscure the disclosure with details that will be readily apparent to those of
ordinary skill in
the art having the benefit of the description herein.
DESCRIPTION
Turning now to FIG. 2 there is shown a schematic view of an example of a head
of a
monostatic scanning LIDAR optical ranging sensor, shown generally at 200,
using a multi-
faceted reflecting mirror, also known as a polygonal mirror, as a first
(energy-)redirecting
element 223, of dual redirecting elements 223, 233 according to the present
disclosure.
FIG. 3 shows a complementary perspective schematic view of the sensor 200
according to
the present disclosure.
In some examples, the sensor 200, may be understood to incorporate, in some
respects,
the first NTC sensor, but where the first independently rotatable mirror,
which, in some
examples disclosed in the first NTC sensor, was a (first) wedge mirror, is
replaced with the
multi-faceted polygonal first redirecting element 223. Because of the
differing configuration
of the first wedge mirror in the first NTC sensor (the first motor shaft is
substantially normal
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to the first motor mount on which the first wedge mirror is mounted at an
angle) and the first
redirecting element 223 in the sensor 200 (the first motor shaft 221 is
substantially parallel
to the planes of each of the facets 222 of the first redirecting element 223),
the axis of the
corresponding first motor shaft 221 driving the first redirecting element 223
in the sensor
200 is substantially normal to the axis of the first motor shaft driving the
first wedge mirror in
the first NTC sensor.
As will be discussed elsewhere, one of such orientations is primarily
controlled by the first
redirecting element 223. Such controlled orientation, which depending upon the
orientation
of the first motor shaft 221 (in Fig. 2 parallel to the C-axis) may be the
azimuthal orientation
(which is the case in Fig. 2) or the elevational orientation, tends to be
expanded relative to
that of the FOV of the first NTC sensor, all other things being substantially
equal.
Additionally, relative to the configuration of the first NTC sensor, the
sensor 200 has a FOV
where the controlled (in Fig. 2 the azimuthal) orientation thereof is
substantially decoupled
from that of the other (in Fig. 2 the elevational) orientation thereof.
Further, as a result of the decoupling of the controlled and uncontrolled
orientations of the
FOV, the FOV tends to have a more rectangular than elliptical or conical shape
than that of
the first NTC sensor.
Still further, the use of the first redirecting element 223 in the sensor 200
tends to more
evenly distribute the energy across the controlled (in Fig. 2, the azimuthal)
orientation of the
FOV relative to the FOV of the first NTC sensor. This more even energy
distribution has
two complementary and salutary implications. First, for a given rated power of
the beam
source 210, there is less concern about eye safety near the centroid of the
FOV. Second,
the rated power of the beam source 210 may be increased while continuing to
satisfy
prevailing eye safety considerations, which may correspondingly increase the
effective
range F? of the sensor 200 and/or the ability of the sensor 200 to deal with
an increased
density of obscurants between the sensor 200 and the target 10.
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In some non-limiting examples, the first redirecting element 223 may be
comprised of one
or more refractive elements (not shown) as opposed to a multi-faceted
reflecting mirror as
shown. In some non-limiting examples, such (set of) refractive element(s) may
comprise
Risley prisms. Those having ordinary skill in this art will appreciate that
using such (set of)
refractive element(s) may cause the axis of the corresponding first motor
shaft 221 driving it
to be different from what is shown in Fig. 2. Further, using such (set of)
refractive
element(s) may cause the two orientations of the resulting FOV to be more
highly coupled
than the example shown in Fig. 2.
Fig. 2 also shows a right-handed cartesian coordinate system with mutually
orthogonal
axes by which the orientation of orientations of the sensor 200 may be
identified,
respectively designated A, B and C and in which the A-axis extends to the
right in the plan
view of Fig. 2, the B-axis extends upward and in the direction of the beam
axis 214 in the
plan view of Fig. 2 and the C- axis extends normally outward from the plan
view of Fig. 2.
The sensor 200 comprises a beam source 210, a first redirecting assembly 220,
a second
redirecting assembly 230, a third redirecting element 240, a detector 250 and
a receiver
unit 260.
The sensor 200 may be considered as comprising a launch portion and a
detection portion.
The launch portion of the sensor 200 may be considered to employ the beam
source 210,
the first redirecting assembly 220 and the second redirecting assembly 230.
The detection
portion of the sensor 200 may be considered to employ the first redirecting
assembly 220,
the second redirecting assembly 230, the third redirecting element 240, the
detector 250
and the receiver unit 260.
Considering first the launch portion of the sensor 200, the beam source 210
generates a
launch beam 213 along a beam axis 214 that extends parallel to and along the
positive B
direction.
In some non-limiting examples, the beam source 210 may be a fiber or other
form of laser.
In some examples, the beam source 210 may be a LED laser. In some non-limiting

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examples, the wavelength of the launch beam 213 may be 1550 nm. In some non-
limiting
examples, the rated power of the beam source 210 may be between substantially
300 mW
and 2W. However, the beam source 210 may be provided with a substantially
larger (or
smaller) rated power depending upon the desired range, capability and/or
sensitivity of the
sensor 200.
The ability to image a target 10 at a given range R of the sensor 200 may
depend upon one
or more of the rated power of the beam source 210, the sensitivity of the
detector 250
and/or how much power is returned from the target 10 and is redirected to the
detector 250.
In some non-limiting examples, the wavelength of the launch beam 213 and/or
the rated
power of the beam source 210 may be constrained by prevailing eye safety
considerations.
In some non-limiting examples, the launch beam 213 is pulsed at a pulse
repetition
frequency (PRF) that may range, without limitation, from as low as 0 Hz (in
the case of a
OW beam) to a maximum capability supported by the sensor 200, recognizing that
the
effective range of the sensor 200 would decrease as the PRF increases. In some
non-
limiting examples, the launch beam 213 is a continuous beam. In some non-
limiting
examples, the launch beam 213 is an FMCW beam, especially if, as discussed
elsewhere,
heterodyne detection of the phase difference is used to determine the range R
to the target
10.
In some non-limiting examples, the beam source 210 is coupled to the receiver
unit 260 by
a signal line 261 such that the receiver unit 260 can correlate the emission
of the launch
beam 213 with the receipt of a signal corresponding thereto by the detector
250 and
determine the range R to the target 10 therefrom.
In some non-limiting examples, the time that the (pulsed) launch beam 213 is
emitted is
correlated with the time at which the corresponding signal is detected at the
detector 250 to
determine a time of flight (TOF) to and from the target 10 from which the
range R thereto
may be determined.
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In some non-limiting examples, the phase at which the (CW) launch beam 213,
which in
some non-limiting examples would be a FMCW beam, is emitted, is correlated
with the
phase at which the corresponding signal is detected by heterodyne detection at
the receiver
unit 260, to determine a phase difference, from which the range R to the
target 10 may be
determined, although it will be appreciated that the specific configuration in
such case
would be different and may involve different and/or additional components from
that shown
in Fig. 2 and as described herein.
In some non-limiting examples, the beam source 210 comprises a laser beam
collimator
212, for collimating the launch beam 213 passing through it, to restrict or
inhibit its
divergence from the beam axis 214. Additionally, in some non-limiting
examples, the
collimator 212 may expand the launch beam 213 to a diameter that is suitable
so that its
energy density is sufficiently low, relative to the rated power of the beam
source 210 and
the wavelength(s) emitted, to satisfy prevailing eye safety considerations.
The first redirecting assembly 220 comprises a first motor (not shown), a
first motor shaft
221 coupled thereto and lying along a first axis 224 that is at a first angle
to the beam axis
214, a first mount (not shown) lying in a plane normal to the first motor
shaft 221 (as shown
in Fig. 2, in the A-B plane) and coupled to the first motor shaft 221, and a
first redirecting
element 223 coupled to the first mount, which in some non-limiting examples,
may be a
facet 222 of a multi-faceted or polygonal element on which the launch beam 213
is incident.
In some non-limiting examples, the first angle between the first axis 224 and
the beam axis
214 may be 900
.
In some non-limiting examples, each of the facets 222 may be a mirrored
surface for
reflecting the launch beam 213, incident thereon at a second (incident) angle
(0) relative to
the plane of the facing facet 222, at a reflected angle (0 having a magnitude
equal to 0, in
.. which case the polygonal first redirecting element 223 may be a polygonal
mirror.
In the orientation of the first motor shaft 221 shown in Fig. 2, as discussed
elsewhere, the
first redirecting assembly 220 is associated with the controlled azimuthal
direction or
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orientation of the FOV and consequently, the second redirecting assembly 230
is
associated with the elevation direction or orientation of the FOV. Typically,
such orientation
may be employed where it is desirable to have a FOV with a controlled
azimuthal
orientation that is long relative to its elevational orientation.
In some non-limiting examples, as shown in Fig. 2, the first motor shaft 221,
which lies
along the first axis 224, may lie parallel to and along the positive C-axis,
in which case the
first mount lies in the A-B plane and the positive A-axis may be considered to
be a third axis
that with the beam axis 214 and the first (positive-C) axis, 224 defines a
right-handed
cartesian coordinate system.
.. In some non-limiting examples, the surface of each of the facets 222 may be
substantially
rectangular in shape and lie in a plane parallel to the C-axis and orthogonal
to the A-B
plane, with the normal vector of each facet 222 lying in the A-B plane. Thus,
as discussed
elsewhere, the first motor shaft 221 lies along a first axis 224 that is
substantially parallel to
the plane of each of the facets 222 of the first redirecting element 223.
In some non-limiting examples, at least one of the facets 222 of the first
redirecting element
223 may be provided with a small facet offset (not shown in Fig. 2), which in
some non-
limiting examples, may be a small number (such as by way of non-limiting
example, less
than 10 ) (or a fraction thereof) of degrees, of the normal vector of each
facet 222 on one or
the other side of the A-B plane. Such facet offset(s) may, as discussed
elsewhere, facilitate
distribution of the first redirected launch beam 215 at a reflected angle
((l)r) to the second
angle (0) that may be substantially of equal magnitude but on the opposing
side of the
normal vector of the facing facet 222, onto different areas of the second
redirecting surface
233 and provide an increase in the extent of the uncontrolled (elevational)
orientation of the
FOV.
Those having ordinary skill in the relevant art will appreciate that the
surface of each of the
facets 222 may still lie (ignoring the possibility of the (small) facet
offset, if any) in a plane
parallel to the C-axis (but be orthogonal to the B-C plane, with the normal
vector of each
facet 222 lying (subject to the facet offset, on one or the other side
thereof) in the B-C
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plane. In such an alternative orientation, the first motor shaft 221, which
lies along the first
axis 224, may lie along and parallel to the positive A-axis (so that the first
motor shaft 221
continues to lie along a first axis 224 that is substantially parallel to the
plane of each of the
facets 222 of the first redirecting element 223) and the positive C-axis may
be considered to
be the third axis that with the beam axis 214 and the first (positive-A) axis
224 still defines a
right-handed cartesian coordinate system. In such an alternative
configuration, the first
mount lies in the B-C plane and the first motor shaft 221 remains normal to
the beam axis
214. Further, as discussed elsewhere, the first redirecting assembly 220
controls or is
otherwise associated with the elevational orientation of the FOV and
consequently, the
second redirecting assembly 230 is associated with the azimuthal orientation
of the FOV.
Typically, such alternative configuration may be employed where it is
desirable to a FOV
with a controlled elevational orientation that is long relative to its
azimuthal orientation.
Nevertheless, for simplicity of description, going forward, only the
configuration shown in
Fig. 2 will be described.
However configured, in some non-limiting examples, each of the facets 222 of
the first
redirecting element 223 have substantially identical dimensions such that,
viewed from the
plan view along the C-axis, the first redirecting element 223 defines a
regular polygon.
The first motor is coupled to the first motor shaft 221 at a first end and can
fully or
completely rotate the first motor shaft 221 in at least one of the clockwise
and counter-
clockwise directions in the A-B plane at a selectable rotation rate. In some
non-limiting
examples, the first motor can fully rotate the first motor shaft 221 about the
first axis 224
thereof in both the clockwise and counter-clockwise direction. In some non-
limiting
examples, the first motor shaft 221 may be completely rotated at a rate
between
substantially 0 rpm and on the order of multiples of 1,000 rpm. The first
motor shaft 221
and thus the first redirecting element 223 is fully rotated by the first motor
through a plurality
of complete revolutions.
The first redirecting assembly 220 is positioned such that the launch beam
213, which exits
the collimator 212 and proceeds unimpeded along the beam axis 214 in the
positive B
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direction thereafter, including through the third redirecting element 240,
impinges on the
surface of a (facing) facet 222 of the first redirecting element 223. Thus, as
the first motor
fully rotates the first motor shaft 221 through multiple complete revolutions,
the first
redirecting element 223 coupled thereto rotates accordingly, presenting one or
another of
the various facets 222, as the facing facet thereof, to the launch beam 213.
The launch
beam 213 impinges on the facing facet 222 and is redirected in a first
redirected launch
beam 215, substantially (subject to the presence of the facet offset, if any)
along the A-B
plane at a second angle onto the second redirecting element 230 as the first
redirecting
element 223 is rotated. In some non-limiting examples, the second angle (0)
may be 45 ,
in which case, in some non-limiting examples, the reflected angle ((l)r) at
which the
redirected radiation from the facing facet 222 is redirected is also
substantially 45 . In
some non-limiting examples, the redirected radiation from the facing facet 222
is evenly
distributed about a range of angles, due to the rotation of the facing facet
222 about the first
axis 224. The angular position of the facing facet 222 determines the
direction
(substantially within the A-B plane) of the redirected radiation. In some non-
limiting
examples, the redirected radiation is incident at a plurality of locations on
and substantially
across the extent of the second redirecting element 233.
The number n of facets 222 forming the first redirecting element 223 will
determine the
maximum angle that the launch beam 213 impinging on the facing facet 222 will
be
redirected. Provided that the dimensions of each of the facets 222 are
substantially
identical, the maximum angular direction, which will increase as the number n
of facets 222
decreases, will be substantially 360 /n. In some non-limiting examples, the
first redirecting
element 223 has n=10 facets such that the maximum angular redirection is 36 .
Additionally, the number n of facets 222 acts as a multiplier of sorts of the
rotational velocity
of the first motor shaft 221 in that, relative to a hypothetical single
faceted mirror being
rotated by the first motor at the same rotational velocity (such as, without
limitation, the first
wedge mirror in the first NTC sensor), the number of scans in the controlled
(azimuthal)
orientation of the FOV by the first redirecting element 223 will be
substantially n times
greater than that of such hypothetical single faceted mirror. This allows a
larger spacing

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between adjacent data points within the FOV, which tends to provide a more
even and
diffuse distribution of energy within the FOV.
The second redirecting assembly 230 comprises a second motor (not shown), a
second
motor shaft 231 coupled thereto and lying along a second axis 234 that is at a
third non-
zero angle to the beam axis 214 and in some non-limiting examples, at a non-
zero angle to
the first axis 224, a second mount 232 coupled to the second motor shaft 231
and a second
redirecting element 233 coupled to the second mount 232. In some non-limiting
examples,
the second redirecting element 233 may be a second mirror surface. In some non-
limiting
examples, the second redirecting element 233 may be substantially circular in
shape.
The second motor is coupled to the second motor shaft 231 at a first end and
can fully or
completely rotate the second motor shaft 231 along the second axis 234 in at
least one of
the clockwise and counter-clockwise directions at a selectable rotation rate.
In some non-
limiting examples, the second motor can fully rotate the second motor shaft
231 about the
second axis in both the clockwise and counter-clockwise direction. In some non-
limiting
examples, the second motor shaft 231 may be completely rotated at a rate
between
substantially 0 and on the order of multiples of 1,000 rpm. The second motor
shaft 231 and
thus the second redirecting element 223 is fully rotated by the second motor
through a
plurality of complete revolutions.
In Fig. 2, both the first motor shaft 221 (along the first axis 224) and the
second motor shaft
231 (along the second axis 234) are shown as rotating in the counter-clockwise
direction.
However, the first motor shaft 221 and the second motor shaft 231 are
independently
rotatable both in terms of speed and direction.
In some non-limiting examples, the second redirecting assembly 230 comprises a
circular
wedge mirror in which the mirror surface comprises the substantially circular
second
redirecting element 233 and is coupled to an angled surface of the second
mount 232
having a wedge-shaped cross-section such as is shown in FIG. 2A. In such
examples, the
second motor shaft 231 is coupled at a second end to a second base 235 of the
second
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mount 232. In some non-limiting examples, the second base 234 of the second
mount 232
defines a plane normal to the axis of the second motor shaft 231.
The second mount 232 supports the mirror surface of the second redirecting
element 233
thereon at a fourth angle, denoted a, to the second axis 234 of the second
mount 232. In
some non-limiting examples, the second mount 232 comprises a triangular prism-
shaped
structure having two identical right-angle triangle-shaped faces and three
rectangular faces
whose opposing sides are corresponding sides of the triangle. One of the
rectangular faces
adjacent to the right angle of the triangle forms the second base 234 of the
second mount
232. The surface of the second redirecting element 233 is parallel to,
supported by and
coupled to the rectangular face opposite to the right angle of the triangle.
The face
opposite the right angle is thus at an angle (90 - a) to the face that forms
the second base
235 of the second mount 232. In some non-limiting examples, the angle (900 -
a) may be in
the range of substantially 00 to 15 . Using a larger angle (90 - a) (or
consequently, a
smaller angle a) may constrain the ability of the surface of the second
redirecting element
233 to capture all the beams redirected by the facing facet 222 of the first
redirecting
element 223 and may adversely impact the amount of the first redirected column
254
(described elsewhere) that may be captured by the sensor 200 for use by the
detector 250.
In some non-limiting examples, the projection of the second axis 234 of the
second motor
shaft 231 in the A-B plane is substantially along the A-axis whereas its
projection in a plane
defined by the A-axis and C-axis (the A-C plane) is substantially at 450 with
the C-axis. In
some non-limiting examples, the projection of the second axis 234 in at least
one of the A-B
plane and the A-C plane may be subject to a small positioning adjustment on
the order of a
few degrees. Such positioning adjustment(s) may be used to more finely
position the
intersection of the azimuthal axis and the elevational axis of the FOV to a
desired location,
such as, without limitation, to better center the projected FOV out of the
enclosure aperture
410 of the enclosure 400 (Fig. 4) (in the case of an adjustment in the A-B
plane) and/or to
better center the FOV extent out of the window (in the case of an adjustment
in the A-C
plane) . In some non-limiting examples, a positioning adjustment of a few
degrees may be
applied relative to the projection of the second axis 234 in the A-B plane.
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The second redirecting assembly 230 is positioned such that the first
redirected launch
beam 215, which is redirected off the facing facet 222 of the first
redirecting element 223 at
the reflected angle ((kr) and proceeds unimpeded thereafter, impinges on the
second mirror
surface 233. Thus, as the second motor rotates the second motor shaft 231
through a
plurality of complete revolutions, the second redirecting assembly 230 rotates
with a
nutation determined by the angle (90 - a) of the plane of the surface of the
second
redirecting element 233 relative to the second base 235 of the second mount
232, so that
the first redirected launch beam 215 impinges upon the second mirror surface
233 and is
redirected at an angle a relative to the second axis 234 of the second motor
shaft 231
outward in a second redirected launch beam 216 toward the target 10. The
amount of
nutation depends upon the angle (90 - a). The bearing of the second
redirected launch
beam 216 depends in part upon the instantaneous rotational angle of the first
redirecting
element 223 and the incident angle (0) presented to the launch beam 213 by the
facing
facet 222 thereof (which dictates the reflected angle (4)0 of the first
redirected launch beam
215 on the surface of the second redirecting element 233) and upon the
instantaneous
rotational angle of the surface of the second redirecting element 233.
In some non-limiting examples, the second redirecting element 233 may be a
refractive
element (not shown) that causes the first redirected launch beam 215 to be
refracted at an
angle a relative to the axis of the second motor shaft 231 in the second
redirected launch
beam 216.
Turning now to FIG. 4, there is shown an example of the sensor 200 within an
enclosure
400. The enclosure 400 comprises an enclosure aperture 410, in a lateral face
thereof,
through which the second redirected launch beam 216 may exit the enclosure
400. In
some non-limiting examples, the enclosure aperture 410 is sized to
substantially permit the
second redirected launch beam 216 to substantially occupy the entire available
FOV.
In some non-limiting examples, the enclosure aperture 410 of the enclosure 400
may be
fitted with a radiation-permeable cover 420, comprising a material that is
transparent at the
frequency of the second reflected launch beam 216, including without
limitation, any one or
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more of acrylic, polycarbonate, glass and/or crystal, to protect the
components of the
sensor 200 both physically and from dust and other contaminants.
FIG. 5 is an example schematic diagram that illustrates respective
contributions of the first
redirecting assembly 220 and the second redirecting assembly 230 shown in Fig.
2 in the
formation of the FOV of the sensor 200. The redirection, by the first
redirecting element
223 of the launch beam 213, which is incident on the facing facet 222 at the
second angle
(0), toward the second redirecting element 233 at the reflected angle WY tends
to produce
a rectilinear FOV 510 that is oriented substantially parallel to the B-axis,
that is, a
substantially horizontal or azimuthal orientation.
By contrast, the redirection of a notional beam (not shown) onto the second
redirecting
element 223 towards the target 10 tends to produce a circular FOV 520 oriented
substantially equally in both the horizontal or azimuthal orientation and in
the vertical or
elevational orientation (substantially parallel to the A-axis). The
combination of the
rectilinear FOV 510 and the circular FOV 520 by successive redirection of the
launch beam
213 by the first redirecting element 223 and then the second redirecting
element 233 tends
to produce a rectangular FOV 530 with a greater extent in the horizontal or
azimuthal
orientation (parallel to the B-axis) relative to the vertical or elevational
orientation (parallel to
the A-axis).
As discussed elsewhere, the first redirecting assembly 220 reflects the launch
beam 213
incident on a facing facet 222 of the first redirecting element 223 in the
first redirecting
assembly 220 as the first redirected launch beam 215, which in turn is
incident on the
second redirecting element 233 of the second redirecting assembly 230.
Also as discussed elsewhere, in some non-limiting examples, the direction of
the second
motor shaft 231, when projected in the A-B plane is, subject to any positional
offset,
substantially in the direction of the positive A-axis and when projected in
the A-C plane is
substantially at 45 relative to the C-axis.
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As the facing facet 222 of the first redirecting element 223 rotates, the
first redirected
launch beam 215 is redirected by the second redirecting element 233
substantially along
the B-axis, subject to the angle (900 - a). If the angle (90 - a) was zero,
the second
redirecting element 233 would redirect the second redirected launch beam 216
substantially
along the positive B-axis, with substantially no A-component, resulting in an
FOV that was
substantially rectilinear. However, since the angle (90 - a) is not zero, the
second
redirecting element 233 redirects the second redirected launch beam 216 with
an additional
component in the A-direction, as a result of the angle (90 - a). Accordingly,
the resulting
FOV, which is projected in the C-direction, will have a substantially
rectangular shape with
.. major and minor axes extending substantially in the A- and B-directions.
The extent of the FOV in the B-direction will be substantially twice the total
angular
redirection provided by the redirection by the facing facet 222 of the first
redirecting element
223, with a further (minor) contribution from the redirection by the second
redirecting
element 233 at the angle (90 - a). The extent of the FOV in the A-direction
will be largely
determined by the value of the angle (90 - a). Therefore, the launch portion
of the sensor
200 distributes the second redirected launch beam 216 in a FOV of
substantially
rectangular dimension toward the target 10. Such rectangular FOV may be, in
some non-
limiting cases, be appropriate to illuminate approaching targets 10 in the
forward direction
of a moving platform to which the sensor 200 is coupled.
The operation of the launch portion of the sensor 200 may now be described. It
will be
appreciated that while the operation of the detection portion of the sensor
200 is being
described independently of the operation of the launch portion of the sensor
200, both the
launch portion and the detection portion operate simultaneously and employ
common
components.
The first redirecting element 223 is fully or completely rotated in a first
direction through at
least one complete revolution and at a first constant rotational rate and the
second
redirecting element 233 is fully or completely independently rotated in a
second direction
through at least one complete revolution and at a second constant rotational
rate. The first

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and second directions may be the same or different and the first and second
constant
rotational rates may be the same or different.
The beam source 210 emits a (pulsed) launch beam 213 and provides data to the
receiving
unit 260 along signal line 261 by which the launch beam 213 may be correlated
with
corresponding returns detected in the detection portion (described elsewhere)
of the sensor
200 to determine the range R to the target 10. The launch beam 213 passes
through and is
conditioned by the collimator 212 and impinges at the incident angle (0) on
the facing facet
222 of the first redirecting element 223, being redirected at the reflected
angle (Cr) as the
first redirected launch beam 215 that impinges on the second redirecting
element 233,
whereupon it is redirected as the second redirected launch beam 216 outwardly
toward the
target 10 in a substantially rectangular scan pattern. As discussed below, the
launch beam
213 passes unimpeded through an aperture 242 in the third redirecting element
240, which
is positioned between the beam source 210 and the first redirecting element
222. In some
non-limiting examples, an optical shroud 241 may also be used to minimize
internal
reflections potentially collected by the third redirecting element 240.
The actual scan pattern of data points that will be displayed in the steady
state depends
upon a number of factors, including without limitation, the pulse rate, the
total scan time, the
rotational direction and/or frequency of the first motor shaft 221, the number
n of facets of
the first redirecting element 220, the rotational direction and/or frequency
of the second
motor shaft 231, the angle (90 - a) of the second redirecting element 233,
the angle
between the first axis 224 and the second axis 234 and the separation between
the facing
facet 222 of the first redirecting element 223 and the second redirecting
element 235.
Adjusting the angle (900 - a) as well as the size of the facets 222 of the
first redirecting
element 223 and the size of the surface of the second redirecting element 233,
will
correspondingly vary the FOV achievable. In some non-limiting examples, an 85
x 210
rectangular FOV (azimuth x elevation) (oriented respectively along the B-axis
and the A-
axis) may be achieved by the sensor 200.
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FIG. 6 illustrates this concept. In these figures, traces of the second
redirected launch
beam 216 have been recorded for a number of simultaneous rotations of the
first motor
shaft 221 and of the second motor shaft 231 as they impinge upon a surface of
the target
10. What can be seen is that substantially linear traces are formed in the
horizontal
direction over a smaller vertical extent, created by the simultaneous and
independent
rotation of the second redirecting element 233. As the number of rotations
increases the
FOV is progressively filled.
The rotational speeds of the first motor shaft 221 and of the second motor
shaft 231 and/or
the phase relationship if any between them impact the form and density of the
scan pattern.
It will also be appreciated that the separation between the facing facet 222
of the first
redirecting element 223 and the second redirecting element 233 may impact the
size of the
second redirecting element 233. As a general rule, the lower the number n of
facets 222 in
the first redirecting element 223, the larger will be the size of the second
redirecting
element 233 in order to capture the first redirected launch beam 215 thereon,
for a given
separation between the first redirecting element 223 and the second
redirecting element
233.
Subject to such constraints as well as power and/or cooling considerations,
those having
ordinary skill in the relevant art will appreciate that there are no practical
limits to how large
and/or how small the sensor 200 may be made. In some non-limiting examples,
the
enclosure 400 of the sensor 200 may be further reduced in size by housing the
beam
source 210 outside the enclosure 400 (not shown). In such circumstances, the
launch
beam 213 is passed into the enclosure 400 by a fibre (not shown) and data from
the beam
source 210 may be sent to the receiving unit 260 by means of a ribbon cable
(not shown).
FIG. 6 shows a non-limiting example simulation of scans made using the launch
portion of
the sensor 200. By way of non-limiting example, the scan 600 shown in FIG. 6
reflects a
pulse repetition frequency (PRF) of 500 kHz, a scan time of 0.3s, a
(counterclockwise,
when seen from above) rotational frequency for the first motor shaft 221 of
5,000Hz, a
(counterclockwise, when seen from above) rotational frequency for the second
motor shaft
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231 of 4,700 Hz, an angle (90 - a) of the second redirecting element 233 of
4.6 , a
separation between the facing facet 222 of the first redirecting element 223
and the second
redirecting element 233 of 2.2cm, an angle of 45 between the first axis 224
and the second
axis 234 and a range R to the target 10 of 200m. The ratio of the rotational
frequency of
the facets 222 of the first redirecting element 223 driven by the first motor
shaft 221 to the
rotational frequency of the second redirecting element 233 driven by the
second motor shaft
231 is thus10.62. The example scan 600 provides a FOV of 85 x 21 .
Turning now to the detection portion of the sensor 200, the impingement on the
target 10 of
at least a portion of the scan pattern in the FOV generated by the second
redirected launch
beam 216 will be redirected by the target 10 as a wall of return radiation
253. In some non-
limiting examples, the return radiation 253 is incident at a plurality of
locations on and
substantially across the extent of the second redirecting element 233.
The directionality and intensity of the return radiation 253 may be impacted,
to a greater or
lesser degree by any one or more of, without limitation:
= the transmitted power of the launch beam 213;
= the cross-sectional size of the launch beam 213;
= the reflectivity of the target 10;
= the physical orientation of the target 10 with respect to the second
redirected launch
beam 216;
= the size of the target 10;
= the range R of the target 10 from the sensor 200; and
= other factors, including without limitation, the presence and/or density
of obscurants
between the sensor 200 and the target 10.
As a result, some but potentially not all, of the return radiation 253, which
is reflected by the
target 10, will impinge upon the second redirecting element 233.
In some respects, the second redirecting element 233 may be said to "sample"
the wall of
return radiation 253. The parameters of the sensor 200, including without
limitation, the
FOV, the angle (90 - a), the size of the facets 222 of the first redirecting
element 223, the
size of the second redirecting element 233 and the separation between the
second
redirecting element 233 and the facing facet 222 of the first redirecting
element 223, may
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be selected to maximize the likelihood that a majority of the return radiation
will find its way
to the receiver 260.
Thus, as the second motor rotates the second motor shaft 231, the second
redirecting
element 233 nutates at the angle (900 - a) about the second axis 234, so that
a sampling of
the return radiation 253 impinges upon the second redirecting element 233 and
is
redirected in a first redirected return column 254. Irrespective of the
breadth and extent of
the return radiation 253 along the second redirecting element 233, a
substantial portion of
the return radiation 253 will be redirected as the first redirected return
column 254 onto the
first redirecting element 223.
The amount of nutation depends upon the angle (90 - a). The bearing of the
first
redirected return column 254 depends in part upon the instantaneous rotational
angle of the
second redirecting element 233.
Some or all of the first reflecting return column 254 may impinge upon the
facing facet 222
of the first redirecting element 223, since the range R is assumed to be small
enough that
the facing facet 222 will be substantially the same at launch and upon
reflection.
In some respects, the facing facet 222 of the first redirecting element 223
may be said to
further "sample" the first redirected return column 254. The parameters of the
sensor 200,
including without limitation, the FOV, the angle (90 - a), the size of the
facets 222 of the
first redirecting element 223 and of the second redirecting element 233 and
the separation
between the second redirecting element 233 and the facing facet 222 of the
first redirecting
element 223, may be selected to maximize the likelihood that a majority of the
first
redirected return column 254 will be so sampled by the facing facet 222 of the
first
redirecting element 223.
The facets 222 of the first redirecting element 223 are sized to ensure that a
sufficient
amount of the first redirected return column 254 is redirected thereon toward
the third
redirecting element 240 to permit detection and ranging of the target 10. The
facing facet
222 of the first redirecting element 223 is sized such that when viewed from
the direction of
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the third redirecting element 240, it appears to substantially fill and in
some non-limiting
examples overfill the view thereof. It will be appreciated that the separation
between the
second redirecting element 233 and the facing facet mirror surface 222 may
consequentially impact the size of the facets 222 of the first redirecting
element 223.
The first redirecting assembly 220 is positioned such that the first
redirected return column
254, which is redirected off the second redirecting element 233 and proceeds
unimpeded
thereafter, impinges upon the facing facet 222 of the first redirecting
element 223. Thus, as
the first motor rotates the first motor shaft 221, the facets 222 of the first
redirecting element
223 rotate about the first axis 224 of the first motor shaft 221 and the first
redirected return
column 254 impinges at an angle corresponding to the reflected angle (4)r)
upon the facing
facet 222 of the first redirecting element 223 and is redirected at an angle
corresponding to
the incident angle (0) having a magnitude equal to (I)r as a second redirected
return column
252 toward the third redirecting element 240. The angular redirection between
the first
redirected return column 254 and the second redirected return column 252 will
depend
.. upon the number n of facets 222 of the first redirecting element 223. The
bearing of the
second redirected return column 252 depends in part upon the instantaneous
rotational
angle of the second redirecting element 233 (which dictates, in part, the
angle of incidence
of the first redirected return column 254 on the facing facet 222 of the first
redirecting
element 223) and upon the instantaneous rotational angle of the facing facet
222 of the first
redirecting element 223 at impingement.
The third redirecting element 240 is a fixed optical element interposed
between the laser
source 210 and the first redirecting assembly 220 and having an optical axis
collinear with
the beam axis 214. The third redirecting element 240 is oriented facing the
first redirecting
element 223 and configured to redirect radiation incident thereon at an angle
to the beam
axis 214, with a small aperture 242 allowing the launch beam 213 to pass
through the third
redirecting element 240 unimpeded.
In some examples, the third redirecting element 240 is a substantially planar,
mirrored
surface oriented at an angle to the optical axis. In some examples, the third
redirecting
element 240 is an offset segment of a parabolic reflecting and focusing
element (not

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shown) configured to redirect radiation thereon at an angle to the optical
axis. In some
examples, the third redirecting element 240 is a refractive element (not
shown) configured
to redirect the radiation incident thereon (in a direction opposite to that of
the launch beam
213) at an angle to the optical axis. In some examples, the angle is
substantially 45 .
However implemented, the bore of the aperture 242 within the third redirecting
element 240
is sized to ensure that the launch beam 213 may pass therethrough unimpeded,
while
substantially minimizing the amount of the second redirected return column 252
that will
pass therethrough. Thus, the launch beam 213 passes through the aperture 242
to
impinge unimpeded upon the facing facet 222 of the first redirecting element
223, while
most if not substantially all of the second redirected return column 252 is
redirected by the
third redirecting element 240 as a third redirected return column 255 toward
the detector
250.
In some respects, the third redirecting element 240 may be said to further
"sample" the
second redirected return column 252. The parameters of the sensor 200,
including without
limitation, the FOV, the angle (90 - a), the size of the facets 222 of the
first redirecting
element 223 and of the second redirecting element 233 and the separation
between the
second redirecting element 233 and the facing facet 222 of the first
redirecting element 223,
as well as the distance between the facing facet 222 of the first redirecting
element 223 and
the third redirecting element 240, the size and angle of the third redirecting
element 240
and the size of the aperture 242, may be selected to maximize the likelihood
that a majority
of the second redirected return column 252 will be so sampled by the third
redirecting
element 240.
In some examples, an optical filter 251 and/or a focusing lens (not shown) is
interposed
along the path of the third redirected return column 255. If a focusing lens
is employed, the
third redirected return column 255 is focused as a focused beam toward a focal
point
proximate to a surface of the detector 250. In some examples, the focusing
lens may be
dispensed with, if the third redirecting element 240 is a parabolic reflecting
and focusing
element (not shown) or a refractive element (not shown), in which case, the
third redirected
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return column 255 itself constitutes the focused beam focused toward the focal
point
proximate to the surface of the detector 250.
If employed, the filter 251 and/or the focusing lens are sized to accept and
pass
therethrough, substantially all of the third redirected return column 255, so
that there is no
"sampling" performed thereby.
Eventually, the focused beam strikes the detector 250.
The detector 250 detects the impingement of the focused beam thereon. In some
examples, the detector 250 may be an avalanche photodiode (APD), a PIN
Photodiode, a
charge-coupled device (CCD), and/or or a receiving fibre connected thereto.
The detector
250 is coupled to the receiver unit 260 such that the receiver unit 260 is
able to correlate
the emission of the launch beam 213 with the receipt of the focused beam
corresponding
thereto by the detector 250 so as to determine a range R to the target 10.
In some non-limiting examples, the detector 250 determines a time when the
focused beam
is detected at the detector 250. The receiver unit 260 then correlates the
time that the
launch beam 213 is emitted with the time at which the corresponding signal is
detected at
the detector 250, from which the receiver unit 260 may determine a TOF to and
from the
target 10, from which the range R thereto may be determined.
In some non-limiting examples, the detector 250 detects, by way of heterodyne
phase
detection, a phase of the focused (OW) beam, which in some non-limiting
examples would
be a FMCW beam. The receive unit 260 then correlates the phase at which the
launch
beam 213 is emitted with the phase at which the corresponding signal is
detected at the
detector 250, from which the receiver unit 260 may determine a heterodyne
phase
difference relative to the corresponding portion of the launch beam 213, from
which the
range R to the target 10 may be determined, although it will be appreciated
that the specific
configuration in such case would be different and may involve different and/or
additional
components from that shown in Fig. 2 and as described herein.
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The receiver unit 260 is coupled to the beam source 210 by signal line 261 and
to the
detector 250 and accepts data therefrom that allows it to determine the range
R to the
target 10.
In some examples, the detector 250 may be fast enough to respond to multiple
return
signals from a single launch beam 213.
In some examples, the receiver unit 260 may comprise and/or be implemented by
a field-
programmable gate array (FPGA) coupled to the beam source 210 and the detector
250.
In some examples, the data obtained by the receiver unit 260 allows the
receiver unit 260 to
derive the TOF between when the (pulsed) launch beam 213 is emitted by the
beam source
.. 210 and when the (pulsed) focused beam corresponding thereto is detected at
the detector
250, from which the range R to the target 10 may be determined.
The mechanism by which the TOF is determined for pulsed beams is well known.
In some
examples the range R may be determined from the TOF by Equation 1:
R = tc/2 (where t is the measured TOF and c is the speed of light)
(1)
In some examples, the data obtained by the receiver unit 260 allows the
receiver unit 260 to
derive a phase difference between the (CW) launch beam 213 that is emitted by
the beam
source 210 and the (OW) focused beam corresponding thereto detected by way of
heterodyne phase detection at the detector 250, from which the range R to the
target 10
may be determined.
The mechanism by which the phase difference is determined for FMCW beams is
well
known.
The coordinates (a, b, c) of detection at range R relative to the A-B-C
coordinate system
are measured by knowing the TOF and the positions of the facing facet 222 of
the first
redirecting element 223 and the second redirecting element 233. Although
encoders can be
.. used to determine the positions of the facing facet 222 of the first
redirecting element 223
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and of the second redirecting element 233, they can be bulky and increase the
cost and
complexity of fabrication. In some non-limiting examples, other methods of
determining the
respective positions of the facing facet 222 of the first redirecting element
223 and the
second redirecting element 233 can be used, including without limitation:
= Hall effect combined with a clock;
= Measurement of back electromotive force (EMF) from the motors combined
with a
clock; and
= Free running motor with an exterior start trigger on every revolution to
start a clock.
.. Thus, the operation of the detection portion of the sensor 200 may now be
described. It will
be appreciated that while the operation of the detection portion of the sensor
200 is being
described independently of the operation of the launch portion of the sensor
200, both the
launch portion and the detection portion operate simultaneously and employ
common
components.
The facets 222 of the first redirecting element 223 are fully and completely
rotated through
at least a complete revolution in a first direction and at a first constant
rotational rate and
the second redirecting element 233 is fully and completely and independently
rotated
through at least a complete revolution in a second direction and at a second
constant
rotational rate. The first and second directions may be the same or different
and the first
and second rotational rates may be the same or different. It will be
appreciated that this is
the same as in the operation of the launch portion of the sensor 200,
described elsewhere.
Some of the return radiation 253, which comprises reflections of the second
redirected
launch beam 216 off the surface of the target 10, impinges on the second
redirecting
element 233, being redirected as the first redirected return column 254 that
impinges on the
facing facet 222 of the first redirecting element 223, whereupon it is
redirected as the
second redirected return column 252 toward the third redirecting element 240.
A portion of
the second redirected return column 252 is redirected by the third redirecting
element 240,
optionally through the filter 251 and/or focusing lens and is focused as a
focused beam
toward a focal point proximate to the surface of the detector 250. The
detector 250 detects
the focused beam and provides data to the receiving unit 260 by which the
focused beam
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may be correlated with corresponding portions of the launch beam 213 in the
launch portion
(described elsewhere) of the sensor 200 to determine the range R to the target
10.
Adjusting the and/or the number n of facets 222 of the first redirecting
element 223, the
angle (90 - CL), as well as the distance between opposing facets 222 of the
first redirecting
element 223 and the diameter of the second redirecting element 233, will
impact the FOV
achievable, perhaps even beyond the FOV shown by non-limiting example in Fig.
6.
Turning now to Fig. 7, there is shown a flow chart, shown generally at 700,
showing
example actions to direct energy radiated from a source along a beam axis to a
coordinate
in an FOV defined by at least one of azimuthal and elevational orientations.
One example action 710 is to rotate a first energy-redirecting element 223
comprising a
plurality n of facets 222 organized in a polygonal configuration completely
about a first axis
224 that is at a first angle relative to the beam axis 214.
One example action 720 is to direct the energy 213 from the source 210 onto
the first
energy-redirecting element 223 at a second angle (0) to a plane thereof.
One example action 730 is to redirect the energy 213 incident on the first
energy-redirecting
element 223, at a reflected angle (il)r) having a magnitude equal to the
second angle (0),
toward a second energy-redirecting element 233.
One example action 740 is to independently rotate, in at least one of
direction and rate
relative to the first energy-redirecting element 223, the second energy-
redirecting element
233 completely about a second axis 234 at a third angle to the beam axis 214.
One example action 750 is to further redirect the energy 215 incident on the
second
energy-redirecting element 233, from the first energy-redirecting element 223,
at a fourth
angle a to the second axis 234 in a direction within the FOV.

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It will be apparent that various modifications and variations may be made to
the
embodiments disclosed herein, consistent with the present disclosure, without
departing
from the spirit and scope of the present disclosure.
In the foregoing disclosure, for purposes of explanation and not limitation,
specific details
are set forth such as particular architectures, interfaces, techniques, etc.
in order to provide
a thorough understanding of the present disclosure. Moreover, an article of
manufacture
for use with the apparatus, such as a pre-recorded storage device or other
similar computer
readable medium including program instructions recorded thereon, or a computer
data
signal carrying computer readable program instructions may direct an apparatus
to facilitate
the practice of the described methods. It is understood that such apparatus,
articles of
manufacture, and computer data signals also come within the scope of the
present
disclosure.
The present disclosure can be implemented in digital electronic circuitry, or
in computer
hardware, firmware, software, or in combination thereof. Apparatus of the
disclosure can
be implemented in a computer program product tangibly embodied in a machine-
readable
storage device for execution by a programmable processor; and methods and
actions can
be performed by a programmable processor executing a program of instructions
to perform
functions of the disclosure by operating on input data and generating output.
The disclosure can be implemented advantageously on a programmable system
including
at least one input device, and at least one output device. Each computer
program can be
implemented in a high-level procedural or object-oriented programming language
or in
assembly or machine language, if desired; and in any case, the language can be
a
compiled or interpreted language. Further, the foregoing description of one or
more specific
embodiments does not limit the implementation of the invention to any
particular computer
programming language, operating system, system architecture or device
architecture.
The processor executes instructions, codes, computer programs, scripts which
it accesses
from hard disk, optical disk (these various disk based systems may all be
considered
secondary storage), ROM, RAM, or the network connectivity devices. Multiple
processors
may be present. Thus, while instructions may be discussed as executed by a
processor,
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the instructions may be executed simultaneously, serially, or otherwise
executed by one or
multiple processors.
When provided by a processor, the functions may be provided by a single
dedicated
processor, by a single shared processor, or by a plurality of individual
processors, some of
which may be shared or distributed. The functions of the various elements
including
functional blocks labelled as "modules", "processors" or "controllers" may be
provided
through the use of dedicated hardware, as well as hardware capable of
executing software
in association with appropriate software with sufficient processing power,
memory
resources, and network throughput capability to handle the necessary workload
placed
upon it. Moreover, explicit use of the term "module", "processor" or
"controller" should not
be construed to refer exclusively to hardware capable of executing software,
and may
include, without limitation, digital signal processor (DSP) hardware, read-
only memory
(ROM) for storing software, random access memory (RAM) and non-volatile
storage.
Suitable processors include, by way of example, both general and specific
microprocessors. Generally, a processor will receive instructions and data
from a read-only
memory or a random access memory. Generally, a computer will include one or
more
mass storage devices for storing data file; such devices include magnetic
disks and cards,
such as internal hard disks, and removable disks and cards; magneto-optical
disks; and
optical disks. Storage devices suitable for tangibly embodying computer
program
instructions and data include all forms of volatile and non-volatile memory,
including by way
of example semiconductor memory devices, such as EPROM, EEPROM, and flash
memory
devices; magnetic disks such as internal hard disks and removable disks;
magneto-optical
disks; CD-ROM and DVD-ROM disks; and buffer circuits such as latches or flip
flops. Any
of the foregoing can be supplemented by, or incorporated in ASICs (application-
specific
integrated circuits), FPGAs (field-programmable gate arrays), DSPs (digital
signal
processors) or GPUs (graphics processing units) including, without limitation,
general
purpose GPU's.
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Examples of such types of computer are programmable processing systems
suitable for
implementing or performing the apparatus or methods of the disclosure. The
system may
comprise a processor, (which may be referred to as a central processor unit or
CPU), which
may be implemented as one or more CPU chips, and that is in communication with
memory
.. devices including secondary storage, read only memory (ROM), a random
access memory,
a hard drive controller, or an input/output devices or controllers, and
network connectivity
devices, coupled by a processor bus.
Secondary storage is typically comprised of one or more disk drives or tape
drives and is
used for non-volatile storage of data and as an over-flow data storage device
if RAM is not
large enough to hold all working data. Secondary storage may be used to store
programs
which are loaded into RAM when such programs are selected for execution. The
ROM is
used to store instructions and perhaps data which are read during program
execution.
ROM is a non-volatile memory device which typically has a small memory
capacity relative
to the larger memory capacity of secondary storage. The RAM is used to store
volatile data
and perhaps to store instructions. Access to both ROM and RAM is typically
faster than to
secondary storage.
I/O devices may include printers, video monitors, liquid crystal displays
(LCDs), touch
screen displays, keyboards, keypads, switches, dials, mice, track balls, voice
recognizers,
card readers, paper tape readers, or other well-known input devices.
The network connectivity devices may take the form of modems, modem banks,
ethernet
cards, universal serial bus (USB) interface cards, serial interfaces, token
ring cards, fiber
distributed data interface (FDDI) cards, wireless local area network (WLAN)
cards, radio
transceiver cards such as code division multiple access (CDMA) or global
system for
mobile communications (GSM) radio transceiver cards, and other well-known
network
devices. These network connectivity devices may enable the processor to
communicate
with an Internet or one or more intranets. The network connectivity devices
may also
include one or more transmitter and receivers for wirelessly or otherwise
transmitting and
receiving signal as are well known. With such a network connection, it is
contemplated that
the processor might receive information from the network, or might output
information to the
network in the course of performing the above-described method steps.
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Such information, which is often represented as data or a sequence of
instructions to be
executed using the processor for example, may be received from and outputted
to the
network, for example, in the form of a computer data baseband signal or signal
embodied in
a carrier wave. The baseband signal or signal embodied in the carrier wave
generated by
the network connectivity devices may propagate in or on the surface of
electrical
conductors, in coaxial cables, in waveguides, in optical media, for example
optical fiber, or
in the air or free space. The information contained in the baseband signal or
signal
embedded in the carrier wave may be ordered according to different sequences,
as may be
desirable for either processing or generating the information or transmitting
or receiving the
information. The baseband signal or signal embedded in the carrier wave, or
other types of
signals currently used or hereafter developed, referred to herein as the
transmission
medium, may be generated according to several well known methods.
Moreover, although some embodiments may include mobile devices, not all
embodiments
are limited to mobile devices; rather, various embodiments may be implemented
within a
variety of communications devices or terminals, including handheld devices,
mobile
telephones, personal digital assistants (PDAs), personal computers, audio-
visual terminals,
televisions and other devices.
In some instances, detailed descriptions of well-known devices, circuits, and
methods are
omitted so as not to obscure the description of the present disclosure with
unnecessary
detail. All statements herein reciting principles, aspects and embodiments of
the
disclosure, as well as specific examples thereof, are intended to encompass
both structural
and functional equivalents thereof. Additionally, it is intended that such
equivalents include
both currently known equivalents as well as equivalents developed in the
future, i.e., any
elements developed that perform the same function, regardless of structure.
Thus, for example, it will be appreciated that block diagrams reproduced
herein can
represent conceptual views of illustrative components embodying the principles
of the
technology.
While the present disclosure is sometimes described in terms of methods, a
person of
ordinary skill in the art will understand that the present disclosure is also
directed to various
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apparatus including components for performing at least some of the aspects and
features of
the described methods, be it by way of hardware components, software or any
combination
of the two, or in any other manner.
Certain terms are used throughout to refer to particular components.
Manufacturers may
refer to a component by different names. Use of a particular term or name is
not intended
to distinguish between components that differ in name but not in function.
The terms "including" and "comprising" are used in an open-ended fashion, and
thus should
be interpreted to mean "including, but not limited to". The terms "example"
and "exemplary"
are used simply to identify instances for illustrative purposes and should not
be interpreted
as limiting the scope of the invention to the stated instances. In particular,
the term
"exemplary" should not be interpreted to denote or confer any laudatory,
beneficial or other
quality to the expression with which it is used, whether in terms of design,
performance or
otherwise.
The terms "couple" or "communicate" in any form are intended to mean either a
direct
connection or indirect connection through some interface, device, intermediate
component
or connection, whether electrically, mechanically, chemically, or otherwise.
Directional terms such as "upward", "downward", "left" and "right" are used to
refer to
directions in the drawings to which reference is made unless otherwise stated.
Similarly,
words such as "inward" and "outward" are used to refer to directions toward
and away from,
respectively, the geometric center of a device, area or volume or designated
parts thereof.
Moreover, all dimensions described herein are intended solely to be by way of
example for
purposes of illustrating certain embodiments and are not intended to limit the
scope of the
disclosure to any embodiments that may depart from such dimensions as may be
specified.
References in the singular form include the plural and vice versa, unless
otherwise noted.
As used herein, relational terms, such as "first" and "second", and numbering
devices such
as "a", "b" and the like, may be used solely to distinguish one entity or
element from another

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entity or element, without necessarily requiring or implying any physical or
logical
relationship or order between such entities or elements.
All statements herein reciting principles, aspects and embodiments of the
disclosure, as
well as specific examples thereof, are intended to encompass both structural
and functional
equivalents thereof. Additionally, it is intended that such equivalents
include both currently
known equivalents as well as equivalents developed in the future, i.e., any
elements
developed that perform the same function, regardless of structure.
Thus, for example, it will be appreciated that block diagrams reproduced
herein can
represent conceptual views of illustrative components embodying the principles
of the
technology.
The purpose of the Abstract is to enable the relevant patent office or the
public generally,
and specifically, persons of ordinary skill in the art who are not familiar
with patent or legal
terms or phraseology, to quickly determine from a cursory inspection, the
nature of the
technical disclosure. The Abstract is neither intended to define the scope of
this disclosure,
which is measured by its claims, nor is it intended to be limiting as to the
scope of this
disclosure in any way.
The structure, manufacture and use of the presently disclosed embodiments have
been
discussed above. While example embodiments are disclosed, this is not intended
to be
limiting the scope of the presently described embodiments. It should be
appreciated,
however that the present disclosure, which is described by the claims and not
by the
implementation details provided, which can be modified by omitting, adding or
replacing
elements with equivalent functional elements, provides many applicable
inventive concepts
that may be embodied in a wide variety of specific contexts. The specific
embodiments
discussed are merely illustrative of specific ways to make and use the
disclosure, and do
not limit the scope of the present disclosure. Rather, the general principles
set forth herein
are considered to be merely illustrative of the scope of the present
disclosure.
In particular, features from one or more of the above-described embodiments
may be
selected to create alternative embodiments comprised of a sub-combination of
features that
may not be explicitly described above. In addition, features from one or more
of the above-
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described embodiments may be selected and combined to create alternative
embodiments
comprised of a combination of features that may not be explicitly described
above.
Features suitable for such combinations and sub-combinations would be readily
apparent to
persons skilled in the art upon review of the present application as a whole.
The subject
matter described herein and in the recited claims intends to cover and embrace
all suitable
changes in technology.
Further, the various elements or components may be combined or integrated in
another
system or certain features may be omitted, or not implemented. Also,
techniques, systems,
subsystems and methods described and illustrated in the various embodiments as
discrete
or separate may be combined or integrated with other systems, modules,
techniques, or
methods without departing from the scope of the present disclosure. Other
examples of
changes, substitutions, and alterations are easily ascertainable and could be
made without
departing from the scope disclosed herein.
It will be apparent that various modifications and variations covering
alternatives,
modifications and equivalents will be apparent to persons having ordinary
skill in the
relevant art upon reference to this disclosure and the practice of the
embodiments
disclosed therein and may be made to the embodiments disclosed herein, without
departing
from the present disclosure, as defined by the appended claims.
Other embodiments consistent with the present disclosure will be apparent from
consideration of the specification and the practice of the disclosure
disclosed herein.
Accordingly the specification and the embodiments disclosed therein are to be
considered
examples only, with a true scope and spirit of the disclosure being disclosed
by the
following numbered claims:
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Representative Drawing